Field of the Invention
The invention relates to a light-emitting device and a manufacturing method thereof, and more particularly, to a light-emitting device for which an LED is used as the light source and a manufacturing method thereof.
Description of Related Art
In a regular white LED structure, a layer of yellow phosphor is covered on a blue LED chip. The mechanism with which the white LED structure emits white light includes emitting blue light via a blue LED chip, wherein a portion of the blue light passes through the yellow phosphor on top and is converted into yellow light, and the yellow light is combined with blue light from other portions to achieve the effect of white light emission. Since the blue light emitted by the blue LED chip has a higher degree of directivity, blue light deviated from the optical axis at a greater angle is weaker, and blue light closer to the optical axis is stronger. Therefore, when blue light is irradiated on fluorescent powder at different intensities, the color temperature of white light correspondingly emitted closer to the optical axis is higher (i.e., blue ratio is high) and the color temperature of white light correspondingly emitted farther from the optical axis is lower (i.e., blue light ratio is low). The phenomenon is also referred to as yellow circle phenomenon, and the color temperature of the light from the white LED structure is not uniform as a result.